So i got this engine in my 86 XJ6s Dont know how or why but when i go to start it after sitting for awhile, it will sound like its firing on minimal cylinders very very rough. it will shoot white smoke everywhere only during this event. ( very noticeable but not extremely concerning) and i have to hold the throttle all the way down till it manages to creep up to 2-2.5k rpms and hold it for about 20 seconds for it to clear up and idle neatly, ive replaced the carb and distributor and overall im just disappointed in the engine. before i started to embark on this endeavor i had a mechanic check it out and i was told it has 150 compression all around, not sure if id be correct to assume the heads would be fine from that reading.
this thing is monstrously slow, stumbles off the line and im getting about 5 miles to a gallon. maybe this would be expected with the weight of the ole jag? ive played with the single barel monojet as much as possible, and im getting around 15 hg from the vaccum no matter what. with the timing set to 5 degrees (yes i removed the vaccume advance) plug are normal looking, maybe a tad wet around the edges, didnt check gap.
id say the only thing out of the ordinary is that im missing the donut on the exhaust and no air cleaner. and the car deisels quite a bit when shut down hot (5-20 seconds with a loud "psshhh" if im lucky from the carb and exhaust.) not sure what a acceptable amount of blowby either, seems to be about a light cigarette puff worth during normal use.
i just cant find an explanation and its killing me. i thought someone did okay with this engine swap its in there good. this thing is in there with what i believe is a th400, what else can i bolt in there?

You guys have been helpful to me so far i and i appreciate the knowledge, this is my first carbureted engine and i was looking forward to throwing some money at it if i can learn enough about whats happening here. this kind of knowledge is lost to so many people, i cant even pay a mechanic to get the car right they wont touch it. so its all up to me!!

 

Gasoline clean and fresh?

Remove the fuel filter and empty the contents into a clean, clear container. What you see will dictate your next steps.

Cheers
DD

 

Hey doug! so i changed the filter and ive seen a pretty decent inscrease in performance. little more power, and id say a major increase in mileage, which looks to be around 10 now instead of 5. but inforntunatly still has the same problems with starting like a steam engine and deiseling when turned off. cant be good for her struggling at 200rpm

As far as the fuel system goes the external fuel pumps (front and back) are a bit loud and take awhile to prime, about 5-6 seconds not familiar with these kind so i dont know if they 'start to go out' or just stop working. been thinking about replacing them soon anyways since they are cheap. This has been my daily driver for almost a month now so gas is definatly fresh.

i havent got the chance to open the fuel filter and look whats in there but the gas that came out was fine. i went ahead and bought another one for later down the road, ill also be changing the oil in the next few days and will examine that a bit closer, looked normal but dirty on the stick.

 

You say you played with that carb... is the carb dripping into the intake while it's not running causing a flooded condition?

 

Hard to check by myself i would have to get a friend to help me, but i noticed two things here and did 1 thing that is getting me VERY close here.

1 When it starts like a train if i open the choke all the way it helps it ALOT to get going
2 I was trying to do more research, i thought maybe accelerator pump. ok, second is timing again, im checking it and noticed my distributor doesnt change when advance is pulled off im thinking i have a more modern(?) one, so i did alot of reading and some people had their timing as high as 12-16 which i thought was absurd seeing as the recommended isnt very high... im not sure why this would differentiate much but i sent the timing to 12, happy, 14 happier.. so i thought it just send it all the way till it started making unwanted noise.. im at around 18-20 right now and it seems very very happy! but there is still a very small loss of throttle when taking off. I was at 2-3 seconds of dead throttle at take off now im at half a second or less of no power during take off. I had the girl chirping tires around a corner i never thought id see that!!!! Its a long shot but i wonder if it could do a wheel stand?

So far ive noticed very minimal dieseling when turned off ( maybe a chug or half a chug compared to 5-15 of them ) and havent done a cold start yet. a little more would solve the problem completely based off what ive done so far, but i cannot turn the distributor any more. Am i just compensating for possibly putting in the distributor wrong here? Im guessing if i missed a tooth installing it, the degree would change by X amount per tooth and be lying to me by that much causing me to have to turn it all the way. please correct me if im wrong.. im really starting to fall in love with this engine and car combo here now that im beginning to understand it. i was also thinking aftermarket cam? Seems to be the least realistic option here but id assume that would change the timing profile farther away from the recomended aswell?

Just hope the car would let me know its unhappy before it explodes from the timing going to the moon



thanks for all the replies guys it means alot to me being able to save this junk yard jag!